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  • Romanian Journal of Morphology and Embryology 2005, 46(3):211223

    Tumoral stroma of salivary pleomorphic adenoma histopathological, histochemical and

    immunohistochemical study CL. MRGRITESCU1), M. RAICA2), CRISTIANA SIMIONESCU1), L. MOGOANT3),

    M. SURPEANU4), F. JAUBERT5), FL. BOGDAN6)

    1)Department of Pathology, Emergency County Hospital, University of Medicine and Pharmacy of Craiova

    2)Department of Cytology and Histology, Victor Babe University of Medicine and Pharmacy, Timioara

    3)Department of Histology, University of Medicine and Pharmacy of Craiova 4)Department of Oral Maxilla Facial Surgery, Emergency County Hospital,

    University of Medicine and Pharmacy of Craiova 5)Department of Pathology, Ren Descartes University Paris V, Faculty of Medicine, Necker Enfants Malades Hospital, France

    6)Research Centre for Microscopic Morphology and Immunology, University of Medicine and Pharmacy of Craiova

    Abstract The aims of our paper were to establish the main histopathological, histochemical and immunohistochemical aspects of tumoral stroma from salivary pleomorphic adenomas. For this purpose we investigated 103 cases by the classical histopathological technique with paraffin embedding and staining with HematoxylinEosin (HE), HematoxylinEosinSafranin (HES), trichromic Masson, trichromic Goldner Szeckelly, orcein and Periodic Acid SchiffBlue Alcian (PASAA). Immunohistochemically, they were investigated for AE1AE3, MNF116, CK8, EMA, vimentin, -actin calponin, S-100, GFAP, collagen IV, and PCNA. The results of our study suggest the key role of neoplastic myoepithelial cell in the achievement of diverse morphological aspects of stroma in such neoplasms. Keywords: pleomorphic adenoma, tumoral stroma, histochemistry, immunohistochemistry.

    Introduction

    The salivary gland pleomorphic adenoma is a benign epithelial neoplasm, histologically characterized by a great diversity of morphological aspects. It is the most common neoplasm of salivary gland origin; its incidence varies in different statistics from 45% to 74% of all the salivary gland tumors [14].

    At the Armed Forces Institute of Pathology (AFIP) the pleomorphic adenomas represent 60 % of the benign tumors from all the salivary gland sites: 61% of the major gland tumors and 54% of the minor gland tumors [5].

    Its structural pleomorphism is given both by the epithelial component, as a result of the cytological differentiations and the growing patterns, and by the stromal component because of its rich morphological and quantitative diversity [5, 6].

    Pleomorphic adenoma is thinly encapsulated. Prominently myxoid tumors often have incomplete capsules, and tumor tissue is juxtaposed against normal gland. This is characteristic of pleomorphic adenoma in the minor glands, where a capsule is rarely well developed.

    Extracellular stroma is one of the defining components of pleomorphic adenoma, ranging from scanty to abundant. According to the relative proportion of stroma and cellular components Seifert subclassified pleomorphic adenoma into four types: type I (stroma

    comprises 3050% of the tumor), type II (stroma comprises ~80% of the tumor), type III (stroma comprises ~2050% of the tumor) and type IV (stroma attains similar proportion to that of type III, but there is focal monomorphic differentiation in the epithelial component) [3].

    The stroma of these tumors may have diverse appearance: myxoid, chondroid, chondro-myxoid, hyaline, fibrous, sclero-hyaline and, very rarely, osseous and adipose. These aspects are usually associated with the predominance of one of them in variable proportion [510].

    The pathognomonic stromal feature of pleomorphic adenoma is the presence of chondro-myxoid stroma. Most pleomorphic adenomas, particularly the long-standing lesions present variable amounts of elastic fibers, which are uncommon in other salivary gland tumors [11, 12].

    Crystalloids composed of collagenous substance; tyrosine and oxalate are more often present in pleomorphic adenoma than in any other salivary gland neoplasm: their incidence varies from 1.5 to 21% [1316].

    Material and methods

    Our study comprised 103 cases of pleomorphic adenomas selected during 10 years, from 1992 until 2001.

  • Cl. Mrgritescu et al.

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    The surgical specimens were provided by the Oral Maxilla Facial Surgery Department of the Emergency County Hospital Craiova, mostly from 1576 year-old females (65 cases), with prevalent parotid localization (77 cases).

    The surgical specimens were routinely fixed with 10% buffered formalin and sent to the Laboratory of Cytology and Pathology of the same hospital. They were processed by the classical histopathological technique with paraffin embedding and stained with HematoxylinEosin (HE), HematoxylinEosinSafranin (HES), trichromic Masson, trichromic Goldner Szeckelly, orcein and Periodic Acid SchiffBlue Alcian (PASAA).

    The immunohistochemical process was made in the Histological, Histopathological and Immuno-histochemical Techniques Laboratory from Victor Babe University of Medicine and Pharmacy Timioara, Department of Cytology and Pathology of the Hospital Necker Enfants Malades from Paris and in the Histological, Histopathological and Immuno-histochemical Techniques Laboratory from University of Medicine and Pharmacy of Craiova.

    We use DAKO LSAB 2 System, HRP technique for AE1AE3, MNF116, CK8, EMA, vimentin, -actin and S-100, and ABC/HRP technique for calponin, GFAP, collagen IV, and PCNA.

    The tumors have been diagnosed according to WHO classification [17].

    In most cases was made an internal control (a positive reaction of the fragments that were placed at a suitable distance away from the tumoral tissue).

    As in immunohistochemistry there is no standard or universal accepted methods to select the histological fields in order to interpret the results (with the exception of PCNA) we used the criteria from literature data [18].

    The intensity of the immunostaining reaction has been described as follows:

    (+++), when the immunostaining reaction is intense positive or all over specific distributed, obvious at small magnification;

    (++), when the immunostaining reaction is focal or with moderate intensity, evident on average magnification;

    (+), when the immunostaining reaction is weak or very focal, visible only at strong magnification;

    (), when the immunostaining reaction is very reduced, to limit;

    (), when the immunostaining reaction is negative.

    Results

    Epidemiological aspect There were selected 103 pleomorphic adenomas

    cases from 283 salivary gland lesions, diagnosed during 19922001.

    In our study the mean age at presentation was 48 years, but the age ranges from the second to eight decades. The patients were mostly females (65 cases,

    representing 63.1%), with a female to male ratio of 1.71 to 1.

    The tumors developed especially in the major salivary glands (76 cases in the parotid, 16 cases in the submandibular glands and two cases in the sublingual gland, all representing about 92% of our casuistry).

    The parotid was the most frequently involved gland (74%). The minor salivary glands were involved in eight cases at the level of the lower lip (three cases), oral mucosa (two cases) and palatine mucosa (three cases).

    Histopathological, histochemical and immunohistochemical aspects of pleomorphic adenomas investigations

    At the tumoral periphery, the stromal tumoral component developed a capsule with variable thickness which did not separate the tumor completely from the rest of the salivary gland (Figure 1a).

    Thus, from 77 typical pleomorphic adenomas with parotid localization 53 presented a capsule that completely surrounded the tumor but with variable thickness in different zones of the tumor.

    From 16 pleomorphic adenomas with submandibular localization only 10 were completely encapsulated. In all the other cases with parotid, submandibular and sublingual localization the tumors were partially encapsulated, in some regions the tumor coming in direct contact with the surrounding glandular parenchyma. In three cases, we have noticed some tumoral prolongation sent through the capsule into the surrounding parenchyma (Figure 1b).

    We have not identified the capsula in any of the cases of pleomorphic adenomas with origin in the minor salivary glands of the oral cavity. In a single case of pleomorphic adenoma we have noticed small neoplastic cell groups with myoepithelial morphology, but without atypia between the collagen fibers that composed the tumoral capsula (Figure 1c).

    According to the relative proportion between the stromal and the parenchyma tumoral components, the 103 cases of pleomorphic adenomas have been classified in four subtypes (Table 1). Table 1 Repartition of the casuistry according to relative

    proportion between tumoral stroma and parenchyma Subtypes of

    pleomorphic adenomasType

    I Type

    II Type

    III Type

    IV No. of all

    cases No. of cases 57 25 12 9 103 Percentage 55% 24% 12% 9% 100%

    In 57 cases of pleomorphic adenomas with stromal predominance the epithelial component was reduced, representing about 20% of the tumoral mass. The neoplastic epithelial proliferations had trabecular, tubular and insular patterns; these small cellular groups were often disposed at the periphery of the myoid stromal component or inside it. In some tumoral areas, the hyaline stromal component created a cylindromatous aspect, which required a differential diagnosis with adenoid cystic carcinoma, its tubular variant.

  • Tumoral stroma of salivary pleomorphic adenoma histopathological, histochemical and immunohistochemical study 213

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